58 ENEMIES OP^ SLUGS AND SNAILS chap. 



is ready to gape.^ Rats also eat Vivipara^ and even Limnaea^ 

 in every part of the world. 



Every kind of slug and snail is eaten greedily by blackbirds, 

 thrushes, chaffinches, and in fact by many species of birds. A 

 thrush will very often have a special sacrificial stone, on which 

 he dashes the shells of Helix aspersa and iiemoralis^ holding them 

 by the lip with his beak, until the upper whorls are broken; 

 heaps of empty shells will be found lying about the place of 

 slaughter. The bearded Titmouse (^Parus hiarynicus) consumes 

 quantities of Succinea j^utris and small Pupa., which are swal- 

 lowed whole and become triturated in the bird's stomach by the 

 aid of numerous angular fragments of quartz.^ 



Frogs and toads are very partial to land Mollusca. A garden 

 attached to the Laboratory of Agricultural Chemistry at Rouen 

 had been abandoned for three years to weeds and slugs. The 

 director introduced 100 toads and 90 frogs, and in less than a 

 month all the slugs were destroyed, and all kinds of vegetables 

 and flowers, whose cultivation had until then been impossible, 

 were enabled to flourish.^ 



Certain Coleoptera are known to prey upon Helices and 

 other land Mollusca. Recluz noticed, near Agde, a beetle 

 (^Staphylinus olens) attack Helix ericetornm when crawling 

 among herbage, sticking its sharp mandibles into its head. 

 Every time the snail retreated into its shell the beetle waited 

 patiently for its reappearance, until at last the snail succumbed 

 to the repeated assaults. M. Lucas noticed, at Oran, the larva 

 of a Drilus attacking a Cyclostoma. The Drilus stood sentinel 

 at the mouth of a shell, which was closed by the operculum, 

 until the animal began to issue forth. The Drilus then with its 

 mandibles cut the muscle which attaches the operculum to the 

 foot, disabling it sufficiently to prevent its being securely closed, 

 upon which it entered and took possession of the body of its de- 

 fenceless host, completing its metamorphosis inside the shell, 

 after a period of six weeks.* The female glow-worm (^Lampyris 

 noctiluca) attacks and kills Helix nemoralis. 



Among the Clavicornia, some species of Silplia carry on a 

 determined warfare against small Helices. They seize the shell 



1 Journ. Trent. N. H. Soc. 1887, p. 58. 2 ^^,^. ^r^^. sist. iii. 1893, pp. 238, 239. 



3 Bev. Nat. Sc. Quest, 1891, p. 261. 



^ Petit de la Saussaye, .Tonrn. de Conch, iii. p. 97 f. 



